Physical Properties of Cometary Nucleus Candidates

5 Pages·2003·0.17 MB·English

by  Jewitt, Davi

Type Progress Report
Grant PHYSICAL PROPERTIES OF COMETARY NUCLEUS
CANDIDATES
Number NAG 5-10437
Period Year 2 of 3:3/01/02-2/28/03 ($58,000)
PI David Jewitt
btstitution Institute for Astronomy, University of Hawaii
2680 Woodlawn Drive
Honolulu, HI 96822
Tel [phone]
e-mail jewitt @ifa.hawaii.edu
Goals
In this proposal we aim to study the physical properties of the Centaurs and the dead comets, these
being the precursors to, and the remnants from, the active cometary nuclei. The nuclei themselves
are very difficult to study, because of the contaminating effects of near-nucleus coma. Systematic
investigation of the nuclei both before they enter the zone of strong sublimation and after they have
depleted their near-surface volatiles should neatly bracket the properties of these objects, revealing
evolutionary effects.
Accomplishments in Year 2
In the second year of this grant we have done the following:
1 Secured data on the Mauna Kea 2.2-m, CFHT, Keck and Subaru telescopes in pursuit of the
proposed physical studies. We have secured measurements primarily in the optical BVRI bands
but also, to a more limited extent, in the near and thermal infrared.
2 We have established that there is a distinct and statistically significant difference between the
surface reflection properties (broadly, "color") of the cometary nuclei and their parents in the
Kuiper Belt. This result is the first to show that the ultrared (and maybe ultraprimitive) matter that
distinguishes the surfaces of many Kuiper Belt Objects (KBOs) is rare or missing on the surfaces
of the cometary nuclei and their inactive remnants. This evolutionary effect has implications for
future NASA studies of comets: we will not sample on the comets the same primitive matter that
wecandetectcolorimetricailyin theKuiperBelt. Thisworkwaspublishedin TheAstronomical
Journal(Jewitt2002)andpresentedaspartofaninvitedtalkatACM Berlin(Jewitt2002b).
12
10
-16 -8 0 $ 16 24 32 40
Reflectivity Gradient. S' [Ck/k_]
Figure 1: Histogram of the color distributions of cometary nuclei (empty histogram) and KBOs
(shaded histogram). The distributions are significantly different. In particular, ultra-red matter (S'
> 25 %/1000,_) is common on the KBOs but missing on the nuclei. From Jewitt (2002a).
3. We have photometrically isolated the nucleus of 143P/Kowal-Mrkos and measured its
rotational properties. This work, together with a detailed analysis of the shape distribution of
cometary nuclei and related bodies, has been submitted for publication in Astronomical Journal.
4. We have conducted a program of observations of asteroid-comet transition object
133P/Elst-Pizzaro. The dust trail identified in 1996 and then thought to be a transient feature
produced by chance collision with a small asteroid (Elst-Pizzaro is itself a dynamically
unremarkable asteroid) has been re-observed in 2002/2003. We find that it is a true cometary
feature, meaning that some main-belt asteroids are ice-rich in their surface regions.
Plans for Year 3
1 We will complete the analysis of 133P and submit this work for publication.
2 We will complete the collection of data for a dust search in the NEO population. This work
will update our earlier paper on profile-fitting, to attempt to narrow the gap between the most
weakly active comets and the apparently inert NEOs.
3 Time acquired on the Keck telescope will be used for thermal-optical measurements of the
Jovian trojan asteroids, objects that share physical similarities with the cometary nuclei. It has long
been thought that the Trojans could be ice-rich beneath their (possibly quite thin) refractory surface
mantles.
Publications of Year 2
• D. Jewitt (2002a). From Kuiper Belt Object to Cometary Nucleus: The Missing Ultra-Red
Matter. Astronomical Journal, 123, 1039-1049.
• D. Jewitt (2002b). From Kuiper Belt to Comet Nucleus. In Proceedings of Asteroids, Comets,
Meteors 2002, ESA Special Publications Series, in press.
• D. Jewitt, S. Sheppard and Y. Fernandez (2003). 143P/Kowal-Mrkos and the Shapes of
Cometary Nuclei. Astron. J., submitted.
" : C
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
RESEARCH GRANT SUPPLEMENT
_J
,_ C:5
03 P,a
To: UNIV HAWAII
2. Grant Number: NAG5-10437
OFRC EOF RESEARCH SERVICES
3. Supplement: 0001
2530 DOLE ST/SAKAMAKI D-200
4. Effective Date: 03/01/2001
HONOLULU, HI96822-3203 U1
o
5. Expiration Date: 02/28/2004
_=:==
(3O
° For research entitled: - C3
PHYSICAL PROPERTIES OF COMETRAY NUCLEUS CANDIDATES
F"
. Under the direction of (Principal Investigator): DAVID JEWrrT
8. Award History. Fundinq History
Previous amount: $55,500.00 Previous obligation: $55,500.00
This action: $58,000.00 This action: $58,000.00
Total to date: $113,500.00 Total obligation to date: $113,500.00
9. Accounting Data: OBJECT CLASS: 4111 PPC: RT B/NC: 805
PCN JON APPROP BLI PC AMOUNT
201-21515 077-344-32-00-06 801/20110(01) A7-01 lC 55,500.00
201-80155 077-344-32-00-06 801/20110(01) A7-01 lC 58,000.00
10. Points of Contact (name of office or individual, address, and telephone number):
Technical Officer: JOHN HILLMAN Property/ ONR, SEA'I'rLE
NASA HEADQUARTERS, CODE S Closeout 1107 N.E. 45TH STREET
WASHINGTON, DC 20546-0001 Administration: SUITE 350
202-358-2314 SEATTLE, WA 98105-4631
206-526-3168
Payment: NASA/Goddard Space Flight Center Grant negotiator: TRACEY A JONES
Cost & Commercial Accounts Department NASA/GSFC, CODE 210.G
Code 155 [phone]
Greenbelt, MD 20771-0001 Letter of Credit: 030
11. This grant is awarded under the authority of 42 U.S.C. 2473 (c) (b'-'),et seq., and is subject to all appflcable laws
and regulations of the United States ineffect on the datd'this grant is awarded, including but not limited to 14
CFR Part 1260 (Grants and Cooperative Agreements).
12. Applicable statement if checked:
__.Y..__. The Federal Demonstration Partnership General Terms and Conditions and NASA
Agency-Specific Requirements to this award.
No change is made to existing provisions or special conditions.
Secondary Administration Delegation
UNITED STATES OF AMERICA Applicabelenclosure(sif)c,hecked:
/_ _ _, Provisions
A /\\,,
Special conditions
I TR'_ACE_A'_ON'_--_t_-- ,( \ _'__(Da_e) - .;';-:- __, Required Publications and Reports
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Contracting "
For access to tlTe NASA Grants and Cooperative Agreement Handbook and status of any future GSFC
Grant awards, visit http:llgenesis.gsfc.nasa.govlgrantslgrants.htm
L
GODDARD SPACE FLIGHT CENTER o
NAG5-10437
AD DITIONAL TERMS
THE PERIOD OF PERFORMANCE IS EXTENDED FOR 24 MONTHS.
THIS SUPPLEMENT PROVIDES FUNDING FOR YEAR 2 OF A MULTI-YEAR PROPOSAL,
THEREFORE A NEW TECHNICAL PROPOSAL IS NOT REQUIRED.